A relay of the kind described above is already known from U.S. Pat. No. 4,618,842. In this known relay, a motor system is arranged on a base, an armature of the motor being arranged at one end of the coil and contact units being provided at the other end of the coil actuated by a pusher arranged above the magnet coil. The contact elements are secured in the base by embedding and the motor system is fixedly connected to the base by means of stops or mating surfaces of the base. Disadvantageously, tolerances of the contact elements and their fastening on one side and of the motor system, including frame and core as well as the armature and pusher, on the other side can accumulate causing deviations of contact gaps or contact overtravel. Consequently, under certain circumstances, erosion safety is not guaranteed.
Further, in the known relay, the armature rests in a groove provided in a bobbin extension, a prolongation of the bobbin or a spring member biasing the armature into its rest position. For coupling the pusher to the armature, the pusher has pins projecting through openings of switching springs. With this kind of coupling, the armature cannot exert a restoring or biasing force against the contact springs. Consequently, in the case of the welding of a contact, a risk exists that the pusher cannot be restored or that the pusher can be restored only by one of a plurality of contact springs causing an indefinite or undesired switching condition.
It is, therefore, an object of the present invention to provide an electromagnetic relay having a simple structure with a simple adjustment between contact elements and the motor unit during assembly.
It is another object of the present invention to provide an electromagnetic relay with a simple adjustment of the motor unit on the base before securing it on the base.
It is still another object of the present invention to provide an electromagnetic relay in which the pusher is reliably coupled to the armature.
It is still another object of the present invention to provide an electromagnetic relay in which the armature is fastened to the yoke and the pusher is coupled to the armature by only one retainer spring.
It is still another object of the present invention to provide a method for assembling an electromagnetic relay and adjusting the same during assembly.